What is a mammogram?

A mammogram is a low dose X-ray of the breast tissue. Mammography is performed to look for early signs of breast cancer before a patient develops symptoms. It can also be used to look for any abnormality when a patient develops a new symptom (a lump or focal pain) in her/his breast tissue.

A routine screening mammogram usually includes at least two pictures of each breast taken at different angles, typically from top to bottom and from side to side. When a mammogram is viewed, breast tissue appears white and opaque (cloudy), and fatty tissue appears darker and translucent (semitransparent).

Screening mammograms are recommended every year for all women starting at age 40. Screening mammograms are also done for women who have no signs or symptoms related to the breasts (asymptomatic).

If there is an abnormality or patients have a new symptom (a lump or focal pain), additional evaluation may be needed. With further examination, most of these questionable abnormalities are found to be normal breast tissue or benign (non-cancerous) tissue.

How often are abnormalities found in a screening mammogram?

Potential abnormalities are found in 6 to 8 percent of women who have screening mammograms. This small group of women needs further evaluation that might include breast physical examination, diagnostic mammography, breast ultrasound, or needle biopsy.

After this additional evaluation is complete, most women who have potential abnormalities on a screening mammogram are found to have nothing wrong.

How does an abnormality appear on a mammogram?

A potential abnormality on a mammogram might be called a nodule, mass, lump, density, or distortion:

  • A mass (lump) with a smooth, well-defined border is often benign.
  • Ultrasound is needed to see and describe the inside of a mass. If the mass contains fluid, it is called a cyst.
  • A mass (lump) that has an irregular border or a starburst appearance (spiculated) might be cancerous, and a biopsy is usually recommended.

Microcalcifications (small deposits of calcium) are another type of abnormality. They can be classified as benign, suspicious, or indeterminate. Most microcalcifications are benign. Depending on how the microcalcifications appear on the additional studies (magnification views), a biopsy might be recommended.

What are the different types of mammograms?

There are two common types of mammograms:

  • Diagnostic Mammogram
  • Digital Mammogram

What is a diagnostic mammogram?

Diagnostic mammograms are done for women who have potential abnormalities that have been detected on a screening mammogram. These mammograms are also done for women who have signs or symptoms related to the breasts (symptomatic). Diagnostic mammograms differ from screening mammograms in that they focus on the potential abnormality or symptom.

Depending on the potential abnormality, different studies might be done. Some women need only additional mammographic images. Other women will have additional mammographic images and an ultrasound.

What is a digital mammogram?

Digital mammograms are newer technology films that use the computer to produce the images. The equipment is very much like a digital camera and can see things better, especially in the case of dense breasts. Digital mammograms are usually recommended for dense breast tissue or for women under the age of 50. The films cannot be lost. However, the amount of compression (squeezing) and radiation is the same as with analog films.

How accurate is mammography?

Mammography is 85 percent to 90 percent accurate. Mammograms have improved the ability to detect breast abnormalities before they are large enough to be felt. However, it is possible that a mass that can be felt (palpable) might not be seen on a mammogram. Any abnormality that you feel when examining your breasts should be evaluated by your health care provider. A diagnostic mammogram might be recommended.

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